The use of phototherapeutic treatment employing low-intensity irradiation has been widely demonstrated to offer benefits in the treatment of various physiological problems and dermatological conditions, such as, but not limited to, carpal tunnel syndrome, tendonitis, bone growth and regeneration, rheumatoid arthritis, wound healing, acne, and general pain control. Phototherapeutic treatment typically affects photoreceptors in the tissue, with consequent alterations in the biochemical processes of the cells. This is accompanied by an increase in local blood circulation and a strengthening of the immune defense system.
In the past several decades, it was also demonstrated that phototherapy is effective in promoting healing of bone, muscle, cartilage, tendon, and ligament. The mechanism in such treatments typically relates to the process of absorption of photons by mitochondria, followed by adenosine triphosphate (ATP) synthesis, which then influences the synthesis of such biological species as proteins, enzymes, DNA/RNA that are required for cell repair or regeneration and for promotion of cell proliferation.
Thus, to summarize briefly, it is widely accepted that absorbed light triggers biological changes within the body, and in such cases, the use of specific wavelengths of light accelerates cellular metabolic processes and stimulates vital chemical reactions. Specifically, phototherapy can (i) increase the circulation by promoting the formation of new capillaries, which accelerate the healing process, (ii) increase DNA/RNA synthesis, which assists damaged cells to be replaced more rapidly, (iii) stimulate collagen protein production, which is important for repairing damaged tissue and replacing old tissue, and (iv) stimulate the release of adenosine triphosphate (ATP) that is a major carrier of energy to cells.
It is important to note that the optical window of the skin, (i.e., a wavelength range with an optimal transmission of light) is in the range between about 600 nm and 1300 nm. Wavelengths, shorter or longer than that range are generally absorbed before reaching substantial depth.
In the case of bone growth and healing, the effect of low level laser therapy (LLLT) on bone regeneration relates to biostimulation of the tissues with monochromatic light. The LLLT has been shown to promote collagen production, accelerate cell proliferation, and enhance bone healing.
The various applications of phototherapy were outlined in various publications, some of which are listed in the References list (see, for example, The science of low-power laser therapy by Karui). It is thought that a low level optical radiation induces biostimulation related to photochemical and photophysical processes on the molecular and cellular levels.
The phototherapy efficacy is related to several major factors. These include spectral range, irradiance (i.e., power per surface area per wavelength), exposed surface area, choice of pulsing frequency, and exposure duration.
Typically, in phototherapy, a careful selection of the spectral content of light used for treatment is required. There were numerous studies confirming the importance of selecting a specific wavelength for phototherapy treatment to be optimal. For example, in the cases of treating wounds, such wavelengths include 680, 730 and 880 nm (Whelan, H. T. et al. J. Clin. Laser Med. Surg., vol. 19, No. 6, 305-314, 2001).
In recent years, numerous reports also clearly demonstrated the beneficial effects of laser phototherapy on bone regeneration and bone fractures. These effects are outlined by Tuner and Hode in “The Laser Therapy Handbook”.
In the studies on bone regeneration, Pinheiro concluded that the use of LLLT at 830 nm substantially improved bone healing at early stages.
Ueda and Shimizu, in the paper entitled “Pulse irradiation of low-power laser stimulates bone nodule formation”, demonstrated the effect of lower-power GaAIAs laser irradiation (830 nm, 500 mW) on acceleration of bone formation as a function of pulse frequency, and concluded that pulsed laser irradiation substantially stimulates bone formation and that pulse frequency is an important factor in bone formation.
De Souza Merli et al., in the paper entitled “Effect of Low-Intensity Laser Irradiation on the Process of Bone Repair”, also showed that the use of low-intensity GaAlAs laser has beneficial effect on bone repair.
In relation to the foregoing discussion, note that visible, especially red and infrared light have been demonstrated to influence many changes at a cellular level. In general, the various tissue and cell types have their own specific light absorption characteristics. In other words, they absorb light at specific wavelengths only. For typically employed wavelength range of 600 to 900 nm, the radiation is absorbed closer to the surface for shorter wavelengths, whereas for longer wavelengths the penetration depth is greater.
In relation to providing therapy to such musculoskeletal system problems as nonunion fractures, spinal fusion, tendon injuries, and osteoporosis, in recent years, several bone stimulation methods for healing were developed (see for example a paper entitled “Enhancement of fracture healing with bone stimulators” by Anglen). Such bone stimulators for promotion of healing typically employ electromagnetic field or ultrasonic signal applied to the bone.
There are different types of electromagnetic field methods used for promoting healing of nonunion bone fractures (i.e., those that do not heal naturally). These include pulsed electromagnetic fields (PEMFs) and direct current methods. These therapy methods to promote healing of nonunion bone fractures were approved by the U.S. Food and Drug Administration (FDA).
Although the advantages of PEMF treatment are well established, in general, the potential hazards of overexposure to electromagnetic fields are widely debated and being explored by various regulatory governing bodies.
Various studies have indicated that electromagnetic fields may pose potential health hazards in such cases of patients as (i) those with cardiac pacemakers or other implanted electrical device, (ii) those with metallic clips and implants, (iii) those who received a localized cortisone injection in the past several weeks, and (iv) pregnant women.
Thus, in relation to the foregoing discussion, it is desirable to provide an apparatus and a method that do not produce such potential health hazards and have a capability of a relatively simpler and more economical means of therapy with fewer risks and harnnful effects, and therefore providing a safer alternative to electromagnetic field methods used in promoting healing of bone fractures.
It is therefore an object of the present invention to provide a novel phototherapy apparatus and method for stimulating bone growth and healing and bone cartilage regeneration.